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Power Surge Protection Guide
By Automated Electrics
Power surges, power spikes, dirty power, however you want to describe them, they are something that cannot be prevented unfortunately and we just have to understand that it does happen within our electricity distribution system. More importantly you need to know that you don’t have to put up with them or suffer their consequences!
We have had numerous calls from plant managers on various sites effected by the recent thunder storms sweeping the country, and we thought it would be a great time to raise the issue of power surge protection so it is in the forefront of people’s minds. We will look at why power surges occur and what you can do to protect yourself against them. Surge protection is an interesting topic that can get quite in-depth, but we will keep this brief and light.
Although in this article we are focusing on power surge protection for the automation industry, you can apply the same theory and methodology for the commercial and residential sectors.
We have had numerous calls from plant managers on various sites effected by the recent thunder storms sweeping the country, and we thought it would be a great time to raise the issue of power surge protection so it is in the forefront of people’s minds. We will look at why power surges occur and what you can do to protect yourself against them. Surge protection is an interesting topic that can get quite in-depth, but we will keep this brief and light.
Although in this article we are focusing on power surge protection for the automation industry, you can apply the same theory and methodology for the commercial and residential sectors.
What are power surges?
Power surges are sudden, sharp high voltage rises in the electricity supply and are one type of electrical disturbance that causes dirty power. The extremely high voltage spikes of a power surge can last for anywhere up to a few milliseconds and damage sensitive electronic equipment and systems.
There are various types of electrical disturbances such as;
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Any disturbance in the mains power is bad, but arguably the most common and one that causes the most damage are the power surges.
What causes power surges?
Power surges occur generally from one of two instances;
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It is estimated that up to 85% of all power surges occur within the customer’s own premises. Surges caused by electrical flow disruptions are the most common and are generally less severe as compared to lighting events. They can occur when a heavy load suddenly stops or is disconnected from the electrical network, for example large motors. When a large motor is stopped, the demand on the electrical transformer in the street that was supplying all of this energy is suddenly reduced. The problem is that the transformer needs to dissipate all of this built up energy in the form of a magnetic field which was used to power the motor. This magnetic field suddenly starts collapsing within the transformer causing a spike in the supply voltage.
The second major cause of power surges are lightning events. With each bolt of lightning producing up to 300,000 amps and one billion volts of electricity, it’s no wonder they can wreak so much havoc! A direct strike to the building itself will cause major issues, but not every building though is susceptible to a direct strike. Depending on a number of factors including the geographical location and surrounding infrastructure, a lot of premises will suffer more from the effects of either a surge coming in through the power lines, or lightning induced surges coming in from underground services. When lightning hits the earth, the energy directed into the ground causes a rise in ground voltage radiating outwards from the point of impact. The high voltage from the lightning strike is then induced into the underground services such as electrical, plumbing and communications that are within this point of impact area.
The second major cause of power surges are lightning events. With each bolt of lightning producing up to 300,000 amps and one billion volts of electricity, it’s no wonder they can wreak so much havoc! A direct strike to the building itself will cause major issues, but not every building though is susceptible to a direct strike. Depending on a number of factors including the geographical location and surrounding infrastructure, a lot of premises will suffer more from the effects of either a surge coming in through the power lines, or lightning induced surges coming in from underground services. When lightning hits the earth, the energy directed into the ground causes a rise in ground voltage radiating outwards from the point of impact. The high voltage from the lightning strike is then induced into the underground services such as electrical, plumbing and communications that are within this point of impact area.
What damage can power surges do?
When you have a look at any electronic product you will see that internally it is made up of small, low powered components that are sensitive and have low voltage thresholds. During a power surge, the voltage on the electrical network spikes and the components within the various electronic devices connected to the network are hit with a voltage that they can’t handle. The voltage thresholds of these electrical components are exceeded, causing them damage.
All power surges will cause some sort of damage, but not all power surges will cause your equipment to instantly fail. A series of smaller surges can end up hurting your electronic equipment just as much as one large surge. Each surge wears the electronic components down bit by bit until one day they will completely fail.
Think of it like a boxer in a fight. There could be one large knockout punch that takes the boxer out in the first round, or their opponent could wear them down with a series of smaller jabs until they are too tired to continue.
One thing is for sure, power surges do happen no matter where you are and they do cause damage!
All power surges will cause some sort of damage, but not all power surges will cause your equipment to instantly fail. A series of smaller surges can end up hurting your electronic equipment just as much as one large surge. Each surge wears the electronic components down bit by bit until one day they will completely fail.
Think of it like a boxer in a fight. There could be one large knockout punch that takes the boxer out in the first round, or their opponent could wear them down with a series of smaller jabs until they are too tired to continue.
One thing is for sure, power surges do happen no matter where you are and they do cause damage!
How can I protect against power surges?
Nobody wants to replace their equipment unnecessarily, and breakdowns are an expensive exercise for any plant or process to go through. That is why it is absolutely crucial that each surge protection design is properly engineered as each installation is different and each plant will have its own requirements that need careful consideration.
A surge protection system should have the following considerations in its design;
Direct Lightning Strikes
As we discussed earlier, not all buildings are at risk of a direct strike. Geographical location, surrounding infrastructure, even the building materials used all play a crucial part in assessing the potential risk of a direct lightning strike. Depending on the site’s risk assessment, protection against lighting strikes can be achieved with something as simple as bonding building structures and grounding systems together, all the way to full blown lightning protection systems with masts in the air that tower over the entire site and guide the lightning strike safely to the grounded earth.
Earthing Installation
A good earthing system is crucial to successful surge protection. You may have the best system available with all the bells and whistles, but if you don’t have a strong earthing system in place it will all be for nothing! The key to surge protection is to give the surge an easy path back to the grounded earth, which is where it is trying to get to. If you cannot provide a strong earth path then it will try and find its way through other means like your electronic equipment, or even worse, YOU! It cannot be underestimated how important earthing is.
Mains Power Reticulation
The mains power reticulation is basically the way your electrical boards are installed and connected to the electricity supply. Starting with the supply from the street, all the way to the final power point on site, your power reticulation network will need careful consideration when it comes to designing your surge protection system. This will determine what type of surge diverters and filters will need to be installed in the various switchboards and control panels on site. We will cover the various types of surge protection units shortly.
Underground Services
Although your site may not be hit directly by lightning, the power surge can still get into your building via the underground services connected to it. Careful consideration needs to be made not only to the power services underground, but also the instrumentation and control cables that connect into the electronic equipment like the PLC and SCADA systems on site. Field instrumentation that is connected by underground wiring generally has surge protection at both the PLC and field ends to ensure the power surge has no affect at either end of the cable.
Communications Services
Power surges are not limited to only the mains power reticulation, they can also come in via the incoming telephone lines and underground communications cabling systems. As with the underground instrumentation, the underground communication wiring generally has surge protection installed at both ends to handle any surges. An alternative to communications surge protection is to replace the copper wiring with fibre optic cables, as the glass fibre optic cables are not effected by magnetic fields or power surges.
Surge Protection Monitoring
After your surge protection system is installed, there will need to be some sort of monitoring plan or system put in place. Basically the surge protection units take the hit of the surge instead of your expensive electronic devices, which means that each surge or hit your site gets will degrade the protection system to some extent. Occasional maintenance will be required down the track to keep the surge protection system fully operational. Surge protection monitoring can be something as simple as a manual periodic inspection or it can be connected to your PLC and SCADA control system for full automatic monitoring and problem notification. Either way you will want to know when your surge protection system needs servicing.
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One thing to remember is that there is no one device that will protect the entire installation. Generally, depending on the manufacturer, there are 3 different classes of surge protection available and each class handles a specific part of the surge.
Class 1 Surge Protection
Class 1 surge protection units are diverters that steer the surge away from the electrical installation and towards the grounded earth which is where the power surge is trying to get to. The main job of a Class 1 unit is to take the brunt of the energy out of the surge so the units below can handle the rest. Generally a Class 1 unit employs spark gap technology and reduces the voltage and power of a surge enough for the Class 2 units downstream.
Class 2 Surge Protection
Class 2 surge protection units are also diverters, like the Class 1 units, and continue on from where the Class 1 units left off. The Class 2 units cannot handle the amount of energy that a Class 1 unit can, but they reduce the voltage of a surge more than what the Class 1 units do. Generally a Class 2 unit employs MOV (Metal Oxide Varistor) technology and reduces the voltage and power of a surge enough for the Class 3 units downstream.
Class 3 Surge Protection
Class 3 surge protection units are power filters that are connected in line with the power to various electronic equipment. Class 3 units have a low discharge capacity and should only be installed after a Class 2 unit. The Class 3 is the final stage of surge protection for your electronic equipment.
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What are the risks of inadequate surge protection?
Unfortunately there are a lot of automation systems out there that do not have any surge protection for their plant’s electronic equipment, and it is possible that they don’t understand the risks they face by not having one. Whether the surge protection system was an over site in the engineering and design phase of the project or it has been left out due to budget restrictions, the lack of surge protection could prove to be a very costly mistake down the track when the owners have to start paying for brand new equipment and parts to replace the ones damaged from a power surge.
The risks of inadequate surge protection include;
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Added to these risks, we are hearing throughout the industry more often that some insurance companies are no longer covering surge damage unless the site has a proper surge protection system installed. After reading this guide you would agree that a surge protection system for your site is an insurance policy you will never be able to beat!
Power Surge Protection Guide
Published By: Automated Electrics
Written By: Chris Orban
Category: Power
Published By: Automated Electrics
Written By: Chris Orban
Category: Power